Service providers are busy developing new innovative products that work on open standards like 
Session Initiation Protocol (SIP). Hosted PBXs are also often called Cloud 
or Virtual PBXs because they are based entirely online through cloud platforms.
One of the prime reasons that such huge cost 
savings benefits exist with a Vo - IP system is that calls traditionally classified as local and 
long distance, are all included in the Vo - IP plans.